The invention concerns a timepiece drive assembly in which a circuit board is carried within a movement casing and is electrically coupled with battery contact terminals.
Such a movement casing arrangement is known for example from DE-P 28 39 556. Therein one of the two battery contact terminals is fastened directly to the circuit board, which in turn is set into the movement casing. The second battery contact terminal is secured to the movement casing itself and applied against a surface of the circuit board by means of a pressure contact for the purpose of simultaneously effecting an electrical connection and the mechanical fastening of the contact terminal by elastic and frictional mechanical means. The ends of the contacts achieving that frictional electric connection of the battery protrude into a battery chamber integral with the movement casing. The battery chamber may, for example in the case of a common casing, be separated from the movement and switching mechanism by a partition disposed inside the movement casing. As the result of the resultant simple and functionally safe assembly of the circuit board, a layout of the battery contact terminals and their arrangement of this type were found to be suitable for movement casings in large clocks, i.e., for the installation of movements in the housing of wall, standing or table clocks with or without date displays. Under certain conditions, however, the fact that the inclusion of the battery chamber in the movement casing necessitates dimensions of the latter that are larger than those required for the housing of the electronic clock circuitry and possibly of an electromechanical drive mechanism for hands and an electromechanical signal transducer device, may prove to be a disadvantage. It may restrict the desirable freedom of design in the development in particular of small cases for timepieces.
A movement for large clocks (made by KUNDO) has been marketed, wherein the two battery contact terminals are fastened to the circuit board and together with it to the movement casing, whereby they protrude freely into the battery chamber, which in turn is readily removable from the rest of the movement casing. This may be an advantage with respect to the replacement of batteries, because the used battery is removed from the casing. However, since the battery connector poles protrude into the center area of the removable battery chamber in order to contact the battery, the overall dimensions of the movement casing are essentially of the same magnitude as those of a battery chamber fixedly attached to the movement casing, i.e., for example of a battery chamber integral with the casing.
It is known from DE-AS 24 03 289 to mount an electromechanical transducer for the movement of the hands directly on the circuit board and further to provide the battery contact terminals in the form of conductor surfaces laminated onto the circuit board itself. The circuit board is not housed in its own movement casing, but is inserted directly into the timepiece housing, wherein the drive batteries are to be inserted between the laminated contact surfaces on the circuit board and a spatially coordinated part of the timepiece housing. This layout eliminates entirely the battery chamber associated with the movement casing, together with the movement casing itself. However, there occurs the disadvantage that in mass producing such circuit boards (desirable from a cost standpoint), the watch case must be adapted to the circuit board, leading to narrow design limitations, at least in relation to the internal layout of the case of the timepiece.
In view of these facts, it is the object of the invention to provide a timepiece drive assembly of the abovedescribed generic type which affords a great degree of design freedom even in timepieces whose housing presents a small volume, and nevertheless is capable of receiving a standardized, mass-produced movement case.